Osseointegrated implants are typically metallic or ceramic screws that may be placed in a bone of a patient for supporting a prosthesis. For example, an osseointegrated implant may include a dental implant for insertion into a jawbone of a patient. Such an implant may support an artificial tooth after the loss of a natural tooth. Replacement of a tooth is often a challenging surgical procedure when the remaining bone has insufficient height to support the implant. For example, replacement of the maxillary teeth is often a challenging surgical procedure when the remaining maxillary bone has insufficient height to support the implant. One surgical technique for augmenting the maxillary bone includes introducing a regenerative material, such as autogenic, allogeneic, xenogeneic, or synthetic bone graft, into the vicinity of the maxillary bone. The regenerative material may form additional bone mass that may integrate with the existing maxillary bone, providing the necessary alveolar height to support the implant.
Bone augmentation procedures are often surgically difficult to perform, and are associated with complications, including infection of the maxillary sinus. The top of the maxillary alveolar ridge forms the floor of the maxillary sinus, and is covered by a thin membrane known as the Schneiderian or subantral membrane. In one surgical procedure, known as a closed or internal sinus lift or elevation procedure, the surgeon drills a bore through the maxillary alveolar ridge from the oral cavity at the desired location of the implant. The bore penetrates the ridge to below the Schneiderian membrane. The surgeon injects the regenerative material through the bore to below the membrane, forming a cavity defined by the top of the ridge and the bottom of the membrane, which cavity occupies a portion of the space initially occupied by the maxillary sinus.
To prevent potentially serious complications, the surgeon must be careful not to perforate the Schneiderian membrane. This is often difficult, because of the delicacy of the membrane, and the restricted access afforded by the closed approach.
Various techniques have been developed to augment bones. One such technique includes a method of lifting a membrane using hydraulic pressure applied by a syringe. A second such technique requires the use of various sinus burs and condensers of increasing width in conjunction with a pliable atraumatic bone grafting mixture and hydraulic pressure from a surgical hand piece. A third technique includes the use of a sleeve to raise the subantral membrane and form a cavity. A filler, such as a bone growth stimulant, may be injected through the sleeve into the cavity. In the process, the sleeve may also cut and/or condense the bone around itself so that the bone may hold an implant. Optionally, the bone growth stimulant may be introduced into the bone surrounding the sleeve. During the injection, the pressure within the sleeve or the cavity may be monitored to detect and prevent the rupture of the subantral membrane.
Further techniques include the use of surgical tools to cut, crack, and push bone from the sinus floor upward into the sinus cavity in a controlled motion. Once the bony sinus floor is cracked free, a fluid passageway may be pressurized with a sterile fluid at a defined pressure to release and push the sinus membrane upward into the sinus cavity which may create a desired apical cavity for grafting. Alternatively, such tools may provide a passageway for carrying fluid through the shank of the tool. Another technique includes the use of an implant comprising at least one shaft area for anchoring in a bony structure, and at least one opening at the distal end of the shaft area in which the shaft area may have a continuous bore extending from the opening to at least one outlet at the apical end, so that targeted introduction of material at least into the periapical area is possible with a stable anchoring in the bone structure even after implantation. Finally, techniques have been developed which may gradually displace periosteal tissue covering bones. The gap developing between the bone and the displaced periosteal tissue may be filled with bone callus as it is in distraction osteogenesis. The techniques allow formation of bone in distraction osteogenesis without cutting a segment of the bone.
Although the above techniques may improve the ability to augment a bone, such techniques may be very complex, invasive, and painful. They may require a very long recovery time and result in temporary disfiguration. Also, patients may experience a high risk of complications, including, for example, tearing of the Schneiderian membrane and infection. Further, such techniques may often be practiced only by very experienced specialists in the maxillofacial field.